Table of Content

20 June 2019 Volume 39 Issue 3

  

Issues

Study on Core Damage of Severe Accidents in EPR Units Using the CDAG Method

Li Jiaming, Yin Yuhao

RADIATION PROTECTION BULLETIN. 2019, 39(3):  1-9. 

Abstract ( 42 )   PDF (15671KB) ( 42 )  

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We introduce core damage evaluation guidelines, and apply Westinghouse's CDAG method to EPR units to study the core damage in severe accidents. CDAG evaluates the core damage degree mainly by judging of two parameters, namely, the containment radiation monitoring value (CRM) and the core outlet thermocouple reading (CET). We discusse the reasons for the differences between CRM and CET in the core damage estimation. The analysis results show that: 1) CDAG is suitable for the core damage evaluation in severe accidents for EPR units; 2) CDAG can reflect the real-time release fraction of fission products in reactors, so as to quickly support the emergency organizations' decision-making; 3) The conservative calculation results of CRM and CET settings based on the EPR design show a reasonable trend and range; 4) Factors such as the releasing way, fuel burn-up, and RCS fission product retention have a great impact on the core damage estimation results.

Alpha Radiation Measurement and Protection in PWR Nuclear Power Plants

Yang Junwu, Yu Enjian, Wang Chuan, Lun Zhenming, Wu Huiyuan

RADIATION PROTECTION BULLETIN. 2019, 39(3):  10-15. 

Abstract ( 110 )   PDF (6299KB) ( 102 )  

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Fuel cladding defects or failure in PWR nuclear power plants (NPP) could result in release of irradiated fuel fragments from fuel assembly into coolant, among which alpha radionuclides dominated bytransuranium may cause systems, equipments, and worksites contaminated, and also increase the risk of internal contamination for workers. NPPs have always paidless attention to this due to the lower probability of occurence, however. We introduces the requirements and procedures, for alpha measurement and protectionin PWR NPPs,of the French Electric Power Company (EDF) and the (United States) Electric Power Research Institute (EPRI). In view of the problems existing in domestic NPPs with respect to alpha contamination control, we make suggestions forimprovement.

The Establishment of Reference Biosphere for Geological Disposal of High Level Radioactive Waste and Its Enlightenment to China

Yang Jie, Lian Bing, Li Yang, Zhao Yangjun, Chen Hailong

RADIATION PROTECTION BULLETIN. 2019, 39(3):  16-21. 

Abstract ( 82 )   PDF (5874KB) ( 99 )  

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Safety evaluation of geological disposal of high level radioactive waste will takes into account the evolution of future biosphere at long time scales. The method of establishing the reference biosphere in the BIOMASS project is highlighted. The reference biosphere can be used to evaluate the specific site of high level radioactive waste. It is recommended to carry out the establishment of reference biosphere of Beishan high level radioactive waste repository as soon as possible.

Articles

Radiation Protection Design of a Halcyon Self-shielding Medical Linear Accelerator Facility

Yang Jun, Lv Yvming, Dong Shengnan

RADIATION PROTECTION BULLETIN. 2019, 39(3):  22-25. 

Abstract ( 135 )   PDF (4759KB) ( 173 )  

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We illustrate environmental and radiation control compliance evaluation formedical accerators, with a Halcyonsystemtaken as an example. Based on analyses of relevant ray parameters and workload, we calculate theshielding thickness of chamber wall in all directions, and the dose rate levelof concern as well. We then optimize the shielding design and construction scheme for the rebuilt of chamber, design an economical and reliable radiation protection scheme, and evaluate the role of self-shielding structure in the shieldingdesign, according to NCRP No.151 and GBZ/T 201, so as to demonstrate that thescheme conforms to relevant laws, regulations and standards. This can also provide a reference for similar projects.

Experimental Determination of the Optimum Operating Environment for Radiation Testing Field

Zhang Hua, LinWeiwei, Xu Runlong, Huang Zhengxuan

RADIATION PROTECTION BULLETIN. 2019, 39(3):  26-32. 

Abstract ( 95 )   PDF (6270KB) ( 124 )  

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The design and construction plan of a radiation testing field in west Guangdong is introduced. A RSS131 high-pressure ionization chamber is used as the transfer instrument to test the calibration coefficient and cosmic ray response of portable radiation monitors, 6150AD and FH40G, under different measurement conditions. The results show that when the maximum gamma dose rate in the field is less than 500 nGy/h, it is more suitable for linear fitting to calculate the cosmic rays response. When it is greater than 500 nGy/h, the calibration coefficient is more suitable to be calculated via linear fitting.

Experiences

Problems and Countermeasures in the Application of Water Sample Gross α and Gross β Radioactivity Analysis Methods in China's Relevant Stardards

Jiang Lan, Wu Guibiao, Zhang Jiajun

RADIATION PROTECTION BULLETIN. 2019, 39(3):  33-36. 

Abstract ( 111 )   PDF (4203KB) ( 247 )  

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We analyzed the problems existing in the practical application of current standard measurement methods forwater sample gross α and gross β radioactivity in China, and proposed the corresponding solutions. It turns out that: 1) The time interval between sample collection and preparation, and between sample preparation and measurement, are not prescribed. For samples with a higher ²²⁴Ra content such as groundwater or rock formation seepage, the analysis should be performed as soon as possible within 48h after sampling, to accurately determine their gross α levels. 2) For samples with a higher amount of residue, which may affect themeasurement accuracy, the detection limit can be reduced by extending the measurement time and using largermeasuring disks. 3) αsources used to determinethe α, βcrosstalk ratio of measuring instruments are not specified. To avoid the crosstalk ratio difference caused by the use of different alpha sources, low background measuring instruments with a relatively low crosstalk ratio, such as those with a build-in solid scintillator or semiconductor detector, can be employed. In addition, aluminum foil, paper, etc. can shield α rays and reduce the influence of α channel on β channel.

Calculation Formula Correction for CF-901 Type Radioactive Aerosol Sampling Pump

Qiao Enjv, Li Jianlong, Chen Ziliang, Hong Binlong, ZHang Zequn

RADIATION PROTECTION BULLETIN. 2019, 39(3):  37-39. 

Abstract ( 75 )   PDF (6134KB) ( 102 )  

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By analyzing the characteristics of two different types of aerosol sampling pump, APEA-GTR and CF-901, and assuming that the sampling, measurement and calculation methods of APEA-GTR type are correct, we have the calculation formula of CF-901 corrected.

Reports

Personal Dose Monitoring and Evaluation for Radiation Diagnosis and Treatment Workers in a Hospital in Chongqing from 2012 to 2018

Ren Xiulong, Gong Jin, Zhang Maolin, Yang Yunfu, Shi Qinhong

RADIATION PROTECTION BULLETIN. 2019, 39(3):  40-43. 

Abstract ( 82 )   PDF (3837KB) ( 58 )  

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We monitored the occupational external exposure in a hospital in Chongqing from 2012 to 2018, using the routinepersonal dosemonitoring method. The results show that the average annual effective dose of radiation diagnosis and treatment staff is 0.3 to 0.8 mSv, which is far below thenational limit. The most exposed is turn out to be those dedicated to interventional radiology, which is followed in turn by radiotherapy, nuclear medicine and radiological diagnosis.

Reviews

Riskand Protection of Oral X-ray Examinations in Pregnant Women

Zhuang Shuqi, Liu Yulong

RADIATION PROTECTION BULLETIN. 2019, 39(3):  44-48. 

Abstract ( 183 )   PDF (5809KB) ( 252 )  

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Pregnancy is a period of high incidence of oral diseases, of which a good diagnosis and treatment cannot be performed without oral X-ray examinations. We presents a literature review on the characteristics of oral diseases in pregnant women, the necessity of oral X-ray examinations for them, and the associated riskand protection as well. And also we recommend that,when the risk of oral diseases during pregnancy is greater than that to the fetus due to X-ray examinations, the corresponding X-ray examinations should be actively accepted.